You will be more than fine with the base model (i5) for what you intend to do (which constitutes very light usage). When people talk about photo editing as being taxing they're talking about professional or semi-professional photoshop editing where the files can weigh hundreds of MB.

The same for video editing really, even though that's heavier than picture editing. When the files become very large and/or you use lots of effects and stuff it can take time to render, but to the casual user it really doesn't make any difference.. I have an iMac from 2007 and that's more than adequate for the video stuff I do.